How to draw a combination curve from data points of two curves with same axes ?

i have data points of two curves with same axes to be drawn in MATLAB. Morever, I need to draw one more curve using all data points of previous two curves with same axes. How can i draw the third curve using all data points of the first two curves? and then, how to find the lowest point of the third curve? I want all of three curves are on one figure. Please give me suggestion.

Answer 1

[Adam Danz]

If your two curves are stored as vectors in variables x1, y1, x2, y2, and you've plotted

figure
plot(x1,y1)
hold on
plot(x2,y1)

then to combine (x1,y1) and (x2,y2) into a 3rd curve,

x3 = [x1, x2];    %for row vectors; if column vecs, [x1;x2]
y3 = [y1, y2]; 
plot(x3,y3)

The lowest point along the y axis in curve #3 is

[minVal, minIdx] = min(y3)

[cloudy snow]

thank you for ur help. actually, i have same values for x axis, and different values for y axis, as attached.. I want to plot the first two curves as (x,y1), (x,y2) and the third curve has same x axis and combination of y values on y axis and to find the min point..does it do the same way?

[Adam Danz]

The method I shared will do what I think you're describing. You just need to make two tiny adjustments: 1) plug in your variable names into my template; 2) use column vectors instead of row vectors (since your data are column vectors).

For example,

y3 = [Y1; Y2];

Note that your 3rd line will literally be on top of your first two lines since you are plotting the same data. To visualize that, here's what I think you're requesting using your data. The black dotted line is Y3 and note how it connects the end of Y1 with the beginning of Y2.

If this is not what you want to do, please try again at describing what you want and if it helps, draw a picture and upload it.

[cloudy snow]

Thanks for ur answer and really appreciate it. i want to automatcially convert multiple .txt files in a folder into .mat file in same folder . How can i do it programatically?

[Adam Danz]

Glad that helped! About your new question, it's best to write a new question on the forum rather than continuing this one since the topic is different. To partially answer the question, it depends on what type of data is being stored in the txt files. Is it strings? numerical matrices? etc.

But first just try searching for the answer because this has been addressed many times.

[cloudy snow]

Thank you for your suggestion..I can solve it now.